It has been reported that radio-labelled butyrophenones, .sup.3 H-haloperidol and .sup.3 H-spiroperidol bind selectively and with high affinity to dopamine receptor sites in mamalian brain and that this specific binding is reduced by neuroleptics in concentrations substantially lower than those occurring in the blood of patients at therapeutic doses.
Creese, J., and Snyder, S. H., Nature, 270, 180-182 (1977) describes an assay for neuroleptics based on competition for such dopamine binding.
It has also reported that benzodiazepines bind to specific receptors on the membranes of rats and human brains and that diazepam specifically binds to brain membranes with high affinity (Squires, R. F., and Braestrup, C., Nature 266, 732-734, (1977) and Braestrup, C., and Squires, R. F., Proc.Natl.Acad.Sci.USA, 74, No. 9, 3805-3809 (1977)). It also appears from these articles that .sup.3 H-diazepam specifically binds to brain membranes with high affinity and that clinically active benzodiazepines have varying ability to displace .sup.3 H-diazepam from the receptors.
Benzodiazepines represent a major group of drugs and for several reasons it would be desirable to determine by a simple, sensitive and specific test procedure the concentration of a psychotropically active benzodiazepine in patient blood or other body liquid after administration of said drug.
The available assays for individual benzodiazepines including gas chromatography, fluorimetry, etc. have not attained routine clinical use because of technical complexities or restrictions of specificity to benzodiazepines.
The object of the invention is to provide a simple, sensitive and specific assay for benzodiazepines in a body liquid, utilizing stable reagents.
Another object of the invention is to provide an assay for benzodiazepines in a body liquid which assay is suitable for routine clinical application.
A further object of the invention is to provide a receptor reagent for use in the process of the invention.
A still further object of the invention is to provide a kit for use in carrying out the process of the invention.